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        검색결과 156

        82.
        2010.10 구독 인증기관·개인회원 무료
        The purpose of this work was to study the effects of electron beam irradiation on development and reproduction and evaluate the DNA damage in Plutella xylostella. Adults and pupae of P. xylostella were irradiated with 30, 50 and 100 Gy electron beam. Hatchability and fecundity of adults declined as increased irradiation doses. When pupae were irradiated with 100 Gy, fecundity of emerged adults significantly decreased and no eggs hatched. However, the adults longevity and emergence of pupae did not change. Assessment of DNA damage in cells obtained from adults and pupae of P. xylostella was carried out using single-cell electrophoresis (comet assay). Electron beam-radiated adults and pupae showed that tail length and percentage of DNA damage at all the doses were significantly larger than the control batch. Our results suggest that electron beam induces sterility through the DNA damage and this technique could contribute to analytical identification of an effective disinfestation and quarantine treatment.
        83.
        2010.06 구독 인증기관 무료, 개인회원 유료
        Enterococcus faecalis, a gram-positive bacterium, has been implicated in endodontic infections, particularly in chronic apical periodontitis. Proinflammatory cytokines, including tumor necrosis factor-α (TNF-α), are involved in the pathogenesis of these apical lesions. E. faecalis has been reported to stimulate macrophages to produce TNF-α. The present study investigated the mechanisms involved in TNF-α production by a murine macrophage cell line, RAW 264.7 in response to exposure to E. faecalis. Both live and heat-killed E. faecalis induced high levels of gene expression and protein release of TNF-α. Treatment of RAW 264.7 cells with cytochalasin D, an inhibitor of endocytosis, prevented the mRNA up-regulation of TNF-α by E. faecalis. In addition, antioxidant treatment reduced TNF-α production to baseline levels. Inhibition of extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein (MAP) kinase also significantly attenuated E. faecalis-induced TNF-α expression by RAW 264.7 cells. Furthermore, activation of NF-κB and AP-1 in RAW 264.7 cells was also stimulated by E. faecalis. These results suggest that the phagocytic uptake of bacteria is necessary for the induction of TNF-α in E. faecalis-stimulated macrophages, and that the underlying intracellular signaling pathways involve reactive oxygen species, ERK, p38 MAP kinase, NF-κB, and AP-1.
        4,000원
        84.
        2010.05 구독 인증기관·개인회원 무료
        The green peach aphid, Myzus persicae (Sulzer), is one of the most serious pest in cabbage cultivation. Field survey was carried out to know the insecticide resistance levels in five main cabbage cultivation regions (Pyeong-chang, Hong-cheon, Bong-wha, Mu-ju and Je-ju) in 2009. The green peach aphid can resist a wide range of insecticides in five surveyed local populations. Among the nine tested insecticides, four chemicals (methomyl, bifenthrin, pymetrozine and flonicarmid) showed less than 50% mortality in the recommended concentration in all populations. Multi resistant (MR) strain was selected from these populations and esterase over-expression, modified AChE (MACE) and mutation(s) in para-type sodium channel were analysed using native IEF and quantitative sequencing with five local populations. Esterase over-expression and MACE (StoF mutation) were observed in all populations including MR strain. LtoF mutation is well known as a kdr mutation in para-type sodium channel. However, even though LC50 values of MR strain noted over 2,000 times higher than that of susceptible strain against bifenthrin, any mutation was not detected in para type sodium channel and also local populations. These results suggested that unusual case could be existed in pyrethroid resistance mechanism in green peach aphid.
        85.
        2009.10 구독 인증기관·개인회원 무료
        The TSSM is one of the most destructive pests on various orchard trees and garden plants. Abamectin resistance mechanisms in two resistant TSSM strains (PTF, ca. 155-fold; AbaR, ca. 3700-fold) were investigated with an emphasis on target site insensitivity mechanism. Detoxification enzyme assays revealed that metabolic factors contributed by EST and/or P450are involved in abamectin resistance. Synergistic assays showed that enhanced detoxification enzyme activity is not enough to account for the high level of abamectin resistance, further suggestive of the involvement of additional resistance mechanism, most likely target site insensitivity. As a putative target site for abamectin, we cloned the cDNA fragments of glutamate-gated chloride channel (Tuglucl) and determined its full length nucleotide sequences. Amino acid sequence comparison among the four strains showed that the Gly323Asp mutation located in the third transmembrane domainis only found in the AbaR strain, suggesting it is likely associated with the target site insensitivity conferring a high level of abamectin resistance.
        86.
        2009.09 구독 인증기관 무료, 개인회원 유료
        Taste is associated with hedonic evaluation as well as recognition of quality and intensity. Taste information is sent to the cortical gustatory area in a chemotopical manner to be processed for discrimination of taste quality. It is also conveyed to the reward system and feeding center via the prefrontal cortices. The amygdala, which receives taste inputs, also influences reward and feeding. In terms of neuroactive substances, palatability is closely related to benzodiazepine derivatives and β-endorphin, both of which facilitate consumption of food and fluid. The reward system contains the ventral tegmental area, nucleus accumbens and ventral pallidum and finally sends information to the lateral hypothalamic area, the feeding center. The dopaminergic system originating from the ventral tegmental area mediates the motivation to consume palatable food. The actual ingestive behavior is promoted by the orexigenic neuropeptides from the hypothalamus. Even palatable food can become aversive and avoided as a consequence of postingestional unpleasant experience such as malaise. The brain mechanism of these aspects of taste is elucidated.
        4,000원
        88.
        2008.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        6,900원
        91.
        2008.09 구독 인증기관 무료, 개인회원 유료
        Reactive oxygen species (ROS) are toxic agents that may be involved in various neurodegenerative diseases. Recent studies indicate that ROS can act as modulators of neuronal activity, and are critically involved in persistent pain primarily through spinal mechanisms. In the present study, whole cell patch clamp recordings were carried out to investigate the effects of tert-buthyl hydroperoxide (t-BuOOH), an ROS, on neuronal excitability and the mechanisms underlying changes of membrane excitability. In current clamp condition, application of t-BuOOH caused a reversible membrane depolarization and firing activity in substantia gelatinosa (SG) neurons. When slices were pretreated with phenyl-N-tert-buthylnitrone (PBN) and ascorbate, ROS scavengers, t-BuOOH failed to induce membrane depolarization. However, isoascorbate did not prevent t-BuOOH-induced depolarization, suggesting that the site of ROS action is intracellular. The t-BuOOH-induced depolarization was not blocked by pretreatment with dithiothreitol (DTT), a sulfhydryl-reducing agent. The membrane-impermeant thiol oxidant 5,5-dithiobis 2-nitrobenzoic acid (DTNB) failed to induce membrane depolarization, suggesting that the changes of neuronal excitability by t-BuOOH are not caused by the modification of extrathiol group. The t-BuOOH-induced depolarization was suppressed by the phospholipase C (PLC) blocker U-73122 and inositol triphosphate (IP₃)receptor antagonist 2-aminoethoxydiphenylbolate (APB), and after depletion of intracellular Cα²+ pool by thapsigargin. These data suggest that ROS generated by peripheral nerve injury can induce central sensitization in spinal cord, and t-BuOOH-induced depolarization may be regulated by intracellular Cα²+ store mainly via PLC-IP₃pathway.
        4,000원
        92.
        2008.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        가석방은 수형자들의 사회복귀의지를 고무하는 교정기법으로 마코노치선장에 의해 시작되었다. 우리의 경우 각 개별시설의 장이 신청서를 작성하여 법무부에 제출하면 법무부 소속 가석방심사위원회에서 심사하여 결정하고 법무부장관의 허가를 얻어 집행한다. 물론 개별시설의 장은 법령에 따라서 일정한 사항을 조사하여 그에 부합하는 수형자를 선발하여 가석방을 받도록 한다. 가석방은 이처럼 의미있는 제도이지만 형기의 얼마를 집행한 후 석방해야 하는지, 석방한 후에는 어떠한 감독과 통제가 따라야 하는지, 본인의 갱생의지는 어떻게 확인해야 하는지, 국가제도로서 시행된 형집행과 어떻게 연계되어야 하는지, 판사의 양형과 교도소관리당국의 수용인원관리라는 형사사법에 어떻게 통일적으로 운영되어야 하는지 많은 문제를 안고 있는 제도이기도 하다. 본 논문은 우리제도 운영과 관련된 서너가지 문제점을 미국연방과 주정부에서 시행하는 가석방을 참고로 하면서 검토해 보았다. 가석방은 교도소수용상태, 일반인의 범죄자에 대한 감정, 적법절차를 고려해야 하지만 무엇보다도 수형자들에게 자립, 갱생의지를 불러 넣어 주는 것이어야 한다. 무엇보다도 가석방 예정기일이 나올 수 있도록 엄정하게 운영할 것, 예정기일보다 상당일수 이전에 가석방대비 프로그램을 다양하게 운영할 것, 가석방대비프로그램을 장기적으로 할 때 수형자의 사회복귀의지를 더욱 더 향상시킬 수 있다고 본다는 주장을 강조했다.
        6,300원
        94.
        2006.09 구독 인증기관·개인회원 무료
        To test the correlation between grain shape and growth behavior we prepared WC-TiC-Co samples with rounded (Ti, W)C grains and faceted WC grains. The growth of rounded (Ti, W)C grains was normal. In contrast, the growth of faceted WC grains was abnormal or suppressed depending on the initial size of WC particles. These observations were explained using growth theories of crystals in a liquid and were also confirmed by a simulation using their growth equations. The present results thus demonstrate that the growth behavior of carbide grains in a liquid is governed only by their shape, irrespective of the presence of another phase.
        95.
        2006.09 구독 인증기관·개인회원 무료
        Two different commercial aluminium powder grades have been densified by direct hot extrusion. The extrusion temperature was 425 °C, with an extrusion ratio of 1:16. Prior to extrusion, some green compacts were pre-sintered (500 °C). The evolution of the extrusion load during the process and the hardness of the final products have been investigated. Additionally, microstructural characterization by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Electron Backscattered Diffraction (EBSD) was carried out. The obtained results evidence grain refinement. Additionally, inter-metallic precipitation, dynamic recovery and geometric dynamic recrystallization take place depending on some process variables, powder composition, heat treatment, strain ...
        96.
        2006.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 논문은 Contour Crafting(CC) 프로세스의 압출과 적층 단계에서 물질 흐름의 형태를 연구하기 위한 실험과 모델링을 보여준다. 특히, 실험재료로써 진흙을 이용한 압출과 적층 메커니즘을 이해하기 위하여 기초적인 유한성분분석(FEA)을 실행하였다. FEA 시뮬레이션을 이용한, CC의 성능에 있어서 압출구멍의 기하학적인 효과에 대한 분명하고 기본적인 이해를 하게 되었다. 네모난 형상이 원하는 외부 표면특성을 만드는 것뿐만 아니라, 그리고 층간에
        5,100원
        97.
        2006.04 구독 인증기관·개인회원 무료
        Capping mechanisms during the compaction of pharmaceutical powders were explored. Both experimental and numerical investigations were performed. For the experimental study, an X-ray Computed Microtomography system has also used to examine the internal failure patterns of the tablets produced using a compaction simulator. Finite element (FE) methods have also been used to analyse the powder compaction. The experimental and numerical studies have shown that the shear bands developed at the early stage of unloading appear to be responsible for the occurrence of capping. It has also been found that the capping patterns depend on the compact shape.
        98.
        2005.10 KCI 등재 구독 인증기관·개인회원 무료
        The purpose 01' pl'esent study was to examine the molecular events in apoptosis by CoCl2, mimicking hypoxic cond ition and recovering effects by LED ir l'adiation on Human SH-SY5Y neuroblastoma cells The SOUl'ce 0 1' light for ir l'adiation was a continuous-wave LED emitting at a wavelenl양h of 590 nm, and manufactured that ene rgy density was 5 mW!cm2 on sample surface, After ir l'adiation, cell viabi lity was measured with BrdU , cell morphol ogy was examined with Diff- Quik staining, cell signaling was monitored with various apoptosis-related molecules using RNase Pl'otection Assay(RPA) , W11en treated with CoC12, apoptotic induction was found in the SH-SY5Y cells in a concentration-dependent and time-dependent manner , Diff-Quik s taining was revealed that DNA fragmentation re presented apoptosis was examined in CoC12-tl'eated group, Moreover, RPA assay of SH-SY5Y cclls lIs ing val'iolls apoptosis-related molecllles showed that the apoptotic cell population was mcreased J-loweve. there was sorne signifïcant change in LED irradiatied cells aftel' treatement of CoC12 The main mechanism for Lhese a poptosis appearecl to be mito c hondriεt - m ecliated pathway, such as cytochrome- c‘ caspase-9, caspase-3, pro-apototic protein ßax, anti-apototic protein Bcl-2, and death receptor• mediated pathway, such as Fas, cas pase- 8, a ncl TNFRl These results demonstrate that CoCI2 induce apoptosis in SH-SY5Y via different dual apop tosis pathway through death receptor pathway as well as mitochondria- dependent pathway and LED irradiation can recl llces the CoCl2-induced apoptosis by blocking their internal signaling pathway
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